Cortical bone growth and maturational changes in the dwarf rat
induced by recombinant human growth hormone .
Martinez, D. A., M. W. Orth, K. E. Carr, R. Vanderby, Jr, and A. C.
Vailas.
Biodynamics Laboratory, University of Wisconsin-Madison, 2000
Observatory Drive, Unit II Madison, Wisconsin 53706, Department of
Orthopaedic Surgery, 600 Highland Ave., University of Wisconsin
-Madison, Madison, Wisconsin 53792
APStracts 2:0195E, 1995.
The GH deficient dwarf rat was used to investigate rhGH induced bone
formation and determine whether rhGH facilitates simultaneous
increases in bone formation and bone maturation during rapid growth.
Twenty dwarf rats, 37 days of age, were randomly assigned to
Dwarf+rhGH (GH n=10) and Dwarf+vehicle (Vehicle n=10) groups. The GH
group received 1.25mg/kg/BW of rhGH, 2x daily for 14 days.
Biochemical, morphological and X-ray diffraction measurements were
performed on the femur middiaphysis. rhGH stimulated new bone growth
in the GH group demonstrated by significant increases (P<0.05)
in longitudinal bone length (6%) middiaphyseal cross-sectional area
(20%) and the amount of newly accreted bone collagen (28%) in the
total pool of middiaphyseal bone collagen. Cortical bone density,
mean hydroxyapatite crystal size and the calcium and collagen
contents ([mu]g/mm3) were significantly smaller in the GH group
(P<0.05). Our findings suggest that the processes regulating new
collagen accretion, bone collagen maturation and mean HAP crystal
size may be independently regulated during rapid growth.
Received 8 March 1995; accepted in final form 7 August 1995.
APS Manuscript Number E109-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 31 October 95